This invention relates to a pulling element with a body having an end which is connectable to a cable to be installed in a duct and having another end, the body being provided with flexible members intended for sealing engagement with the inner wall of such a duct.
Such a pulling element for the purpose of installing cables, in particular telecommunication cables, in a duct is known from British patent application 2,152,621. In the method described in that application, a reduced pressure is created at one end of the duct, and the pulling element having attached thereto the cable or a leader for a cable to be installed is inserted into the duct at the other end thereof. As a result of the pressure difference created, the pulling element is displaced through the duct and thus the cable or the leader is installed in the duct. In the known pulling element, flexible members serve to ensure that when the diameter of the duct varies, the flexible members are in engagement with the inner wall of the duct at all times, because otherwise the reduced pressure at the front of the pulling element would have no effect or too little effect. Variation in the diameter of the duct can occur not only with a duct having an irregular inner diameter, but also at the transition from a duct with a first diameter to a duct with a second, different diameter.
A drawback of the known pulling element is that the diameter variations that can be accommodated are relatively small, in accordance with a maximum travel of coil springs.